Thinly slice the onion, garlic and ginger. Peel and dice the squash. Cut the carrot into small pieces.
Heat the oil in a saucepan and gently sauté the onion for 5 minutes, then add the garlic, ginger, mustard seeds and cumin seeds.
Fry for a couple of minutes, then add the ground spices, stir for a minute until fragrant, then add the chopped tomatoes. Stir for a minute or so, then stir in the lentils. Add the chopped squash and carrots, stir to coat them well. Season with salt and pepper.
Add enough water to cover the vegetables well, then add the bay leaf, star anise, cinnamon and curry leaves.
Bring to the boil, cover and gently simmer over low heat for about 25-30 minutes until the vegetables are soft.
Using a potato masher, crush the squash until you get a thick, textured, creamy stew. Serve with a drop of lemon juice squeezed on top. You can add some chopped coriander leaves too.